Product Code Database
The gigabyte ()The prefix may be pronounced two ways.
is a multiple of the unit byte for digital information. The SI prefix giga- means 109 in the International System of Units (SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB.
This definition is used in all contexts of science (especially data science), engineering, business, and many areas of computing, including storage capacities of hard drives, solid-state drives, and tapes, as well as data transmission speeds. The term is also used in some fields of computer science and information technology to denote (10243 or 230) bytes, however, particularly for sizes of RAM. Thus, some usage of gigabyte has been ambiguous. To resolve this difficulty, IEC 80000-13 clarifies that a gigabyte (GB) is 109 bytes and specifies the term gibibyte (GiB) to denote 230 bytes. These differences are still readily seen, for example, when a 400 GB drive's capacity is displayed by Microsoft Windows as 372 GB instead of 372 GiB. Analogously, a memory module that is labeled as having the size "" has one gibibyte () of storage capacity.
In response to litigation over whether the makers of electronic storage devices must conform to Microsoft Windows' use of a binary definition of "GB" instead of the metric/decimal definition, the United States District Court for the Northern District of California rejected that argument, ruling that "the U.S. Congress has deemed the decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce.
In 1998 the International Electrotechnical Commission (IEC) published standards for , requiring that the gigabyte strictly denote 10003 bytes and gibibyte denote 10243 bytes. By the end of 2007, the IEC Standard had been adopted by the IEEE, European Union, and NIST, and in 2009 it was incorporated in the International System of Quantities. Nevertheless, the term gigabyte continues to be widely used with the following two different meanings:
For RAM, the JEDEC memory standards use IEEE 100 nomenclature which quote the gigabyte as (230 bytes).
The difference between units based on decimal and binary prefixes increases as a Semilog (linear-log) function—for example, the decimal kilobyte value is nearly 98% of the kibibyte, a megabyte is under 96% of a mebibyte, and a gigabyte is just over 93% of a gibibyte value. This means that a 300 GB (279 GiB) hard disk might be indicated variously as "300 GB", "279 GB" or "279 GiB", depending on the operating system. As storage sizes increase and larger units are used, these differences become more pronounced.
Earlier lawsuits had ended in settlement with no court ruling on the question, such as a lawsuit against drive manufacturer Western Digital. Western Digital settled the challenge and added explicit disclaimers to products that the usable capacity may differ from the advertised capacity.
Seagate was sued on similar grounds and also settled.
Software allocates memory in varying degrees of granularity as needed to fulfill data structure requirements and binary multiples are usually not required. Other computer capacities and rates, like Computer storage hardware size, data transfer rates, , FLOPS, etc. are usually presented in decimal units. For example, the manufacturer of a "300 GB" hard drive is claiming a capacity of , not 300 × 10243 (which would be ) bytes.
/ref>
Definition
The term gigabyte has a standard definition of 10003 bytes, as well as a discouraged meaning of 10243 bytes. The latter binary usage originated as compromise technical jargon for byte SI prefix that needed to be expressed in a power of 2, but lacked a convenient name. As 1024 (210) is approximately 1000 (103), roughly corresponding to SI multiples, it was used for binary multiples as well.
Base 10 (decimal)
Based on powers of 10, this definition uses the prefix giga- as defined in the International System of Units (SI). This is the recommended definition by the International Electrotechnical Commission (IEC).http://physics.nist.gov/cuu/Units/binary.html Prefixes for binary multiples This definition is used in computer network contexts and most storage media, particularly , Flash memory-based storage, SanDisk USB Flash Drive "Note: 1 megabyte (MB) = 1 million bytes; 1 gigabyte (GB) = 1 billion bytes." Storage Chart "Megabyte (MB) = 1,000,000 bytes; 1 Gigabyte (GB) = 1,000,000,000 bytes; 1TB = 1,000,000,000,000 bytes" and , and is also consistent with the other uses of the SI prefix in computing, such as CPU clock speeds or FLOPS. The file manager of Mac OS X version 10.6 and later versions are a notable example of this usage in software, which report files sizes in decimal units.
Base 2 (binary)
The binary definition uses powers of the base 2, as does the architectural principle of Binary code .
This usage is widely promulgated by some , such as Microsoft Windows in reference to computer memory (e.g., RAM). This definition is synonymous with the unambiguous unit gibibyte.
Consumer confusion
Since the first disk drive, the IBM 350, disk drive manufacturers expressed hard drive capacities using decimal prefixes. With the advent of gigabyte-range drive capacities, manufacturers labelled many consumer hard drive, solid-state drive and USB flash drive capacities in certain size classes expressed in decimal gigabytes, such as "500 GB". The exact capacity of a given drive model is usually slightly larger than the class designation. Practically all manufacturers of hard disk drives and flash-memory disk devices continue to define one gigabyte as , which is displayed on the packaging. Some operating systems such as Mac OS X, iOS, Android, Ubuntu, and Debian express hard drive capacity or file size using decimal multipliers, while others such as Microsoft Windows (including Windows Phone) report file size using binary multipliers. This discrepancy causes confusion, as a disk with an advertised capacity of, for example, (meaning , equal to 372 GiB) might be reported by the operating system as "".
US lawsuits
A lawsuit decided in 2019 that arose from alleged breach of contract and other claims over the binary and decimal definitions used for "gigabyte" have ended in favour of the manufacturers, with courts holding that the legal definition of gigabyte or GB is 1 GB = 1,000,000,000 (109) bytes (the decimal definition). Specifically, the courts held that "the U.S. Congress has deemed the decimal definition of gigabyte to be the 'preferred' one for the purposes of 'U.S. trade and commerce' .... The California Legislature has likewise adopted the decimal system for all 'transactions in this state'."
Other contexts
Because of their physical design, the capacity of modern computer random-access memory devices, such as DIMM modules, is always a multiple of a power of 1024. It is thus convenient to use prefixes denoting powers of 1024, known as binary prefixes, in describing them. For example, a memory capacity of (10243 B) is conveniently expressed as 1 gibibyte rather than as 1.074 GB. The former specification is, however, often quoted as "1 GB" when applied to random-access memory.
Examples of gigabyte-sized storage
Unicode character
The "gigabyte" symbol is encoded by Unicode at code point .
See also
External links
|
|
